<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>border</title>
    <style>
        .box {
            border-style: solid;
            border-width: 100px;
            border-color: #f00 #0f0 #00f;
        }
    </style>
</head>
<body>
    <div class="box"></div>
</body>
</html>